spring5.x版本 java配置和annotation配置说明

末蓝、 2022-05-30 08:50 71阅读 0赞

java配置

@Configuration //这个注解的意思是相当于把此类当作一个xml文件
    public class AppConfig {
    	
    	@Bean(name="userService")  //这个注解相当于xml文件里的<bean> 
    	public UserService userService() {
    		UserService service = new UserService();
    		service.setUserDAO(userDAOIml());
    		return service;
    	}
    	
    	@Bean
    	public UserDAOIml userDAOIml() {
    		return new UserDAOIml();
    	}
    	
    }

public class UserServiceTest {
    
    	@Test
    	public void testAdd() {
    		ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
    //		UserService service = (UserService)context.getBean(UserService.class);
    		UserService service = (UserService)context.getBean("userService");
    		User user = new User();
    		user.setName("xxx");
    		user.setPassword("123456");
    		service.add(user);
    	}
    
    }

这样就不需要XML文件了。直接用类名或者Bean名都可以获取。

Annotation配置

首先XML配置

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:context="http://www.springframework.org/schema/context"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context.xsd">
    
    
        <context:annotation-config/>
    
        <context:component-scan base-package="com"/>
        
    
    </beans>

接着用@Repository配置这两个实现同一个接口的DAO。

@Repository
    public class UserDAOIml implements UserDAO {
    	@Override
    	public void save(User user) {
    		// TODO Auto-generated method stub
    		System.out.println("UserDAOIml: -----save a user");
    	}
    }
    
    
    @Repository
    public class UserDAOIml2 implements UserDAO {
    	@Override
    	public void save(User user) {
    		// TODO Auto-generated method stub
    		System.out.println("UserDAOIml2: -----save a user");
    	}
    }

接下来配置调用的类

@Service
    public class UserService {
    	@Autowired
    	@Qualifier("userDAOIml2")   //如果没有这句就会报错，Spring不知道该注入哪个实现类
    	private UserDAO userDAO;
    
    	public UserService() {
    		// TODO Auto-generated constructor stub
    		System.out.println("初始化");
    	}
    	
    	public UserDAO getUserDAO() {
    		return userDAO;
    	}
    	
    	public void setUserDAO(UserDAO userDAO) {
    		this.userDAO = userDAO;
    	}
    	
    	public void add(User user) {
    		userDAO.save(user);
    	}
    }

试过不加@Service也能运行成功，暂时不知道啥情况

调用方法

@Test
    	public void testAdd() {
    		ApplicationContext context = new ClassPathXmlApplicationContext("benasAnnotation.xml");	
    		UserService service = (UserService)context.getBean(UserService.class);
    		User user = new User();
    		user.setName("xxx");
    		user.setPassword("123456");
    		service.add(user);
    	}
    
    }

Spring提供四种配置bean的注解。目前测试暂时效果都一样的

@Component      @Controller    @Service        @Repository   回头用的时候再补充吧